Effect of nickel oxide nanoparticles on bioethanol production: Process optimization, kinetic and metabolic studies

•Nickel oxide nanoparticles inclusion improved ethanol concentration up to 19 %.•Optimum conditions for NiO NPs supplemented fermentation were established.•Three kinetic models were used to describe batch fermentation with NiO NPs inclusion.•NiO NPs enhanced total cell protein and carbohydrate accumulation.•Presence of NiO NPs substantially reduced volatile compounds concentration.